Bioaccumulation of heavy metals by Vibrio alginolyticus isolated from wastes of Iron and Steal Factory, Helwan, Egypt

Document Type : Original Article

Authors

1 Botany Department, Helwan University

2 Microbiology Department, Ain Shams University

Abstract

The isolation of bacteria resistant to heavy metals is a topic of interest in the field bioremediation of contaminated water, soil and sediments. We report here the isolation of bacteria that is resistant to high concentration of a mixture of heavy metals namely cadmium, cupper, lead and zinc. The bacterial isolate was obtained from a site receiving heavy metal waste from the iron and steal factory; a major factory located in El-tebeen, south Helwan. The isolate was identified as Vibrio alginolyticus using the API system. The maximum tolerable concentration was 2.5 mM, 4 mM, 2.5 mM and 3.5 mM for cadmium, copper, lead and zinc respectively. Transmission electron micrograph of Vibrio alginolyticus grown in nutrient broth containing a mixture of the four tested heavy metals, showed bioaccumulation of heavy metal(s) on the bacterial cell wall. At the same time, there was an over all reduction in the concentration of heavy metals in culture supernatant; the percentage reduction was 20% for cadmium, 31% for cupper 40% for lead and 45%for zinc. The reduction occurred after 4 hrs incubation at 30°C for all metals, cupper, lead, and zinc  while cadmium required  24 hrs incubation were required to achieve maximum reduction. This isolate could be used to accelerate the in situ bioremediation of sites contaminated by loads of mixed metals.

Keywords